Dentures are removable appliances designed to provide a replacement for teeth and surrounding tissue. In general, certain types of dentures for the upper or lower jaw use a milled denture bar (also called an implant bar) made out of a strong biocompatible metal or alloy such as, for example, titanium, a titanium alloy, a cobalt alloys, a chromium alloy, a palladium alloy, a tantalum alloy, or a zirconium alloy and is connected to the jaw by, for example, screws, and forms the supporting structure for a removable overdenture prosthesis containing false teeth.
Such denture bars typically include some type of attachment, commonly a ball attachment or locator designed to correspondingly mate with a component of a superstructure of the overdenture to keep the overdenture in place on the person during normal activity, while allowing it to be removed periodically, for example, for cleaning.
These types of dental prostheses are often recommended for people with two types of malocclusion, the types known as Class II distocclusion (also known as retrognathism, overjet, or overbite) and Class III mesiocclusion (also known as prognathism, negative overjet, or underbite), however, doing so creates a problem, particularly for people with a powerful bite, because those conditions tend to cause the overdenture to dislodge in the rear.
To the extent denture bar and overdenture prostheses are used on patients with Class II distocclusion or Class III mesiocclusion, the dislodgment problem is typically addressed by using small locking screws or a plunger mechanism (“locking mechanism”)) to affix the rear of the overdenture to the denture bar. However, this requires the denture wearer to use a small screwdriver, wrench, key or other appropriate implement to remove the locking mechanism every time the overdenture needs to be removed. This solution is inconvenient, problematic for persons with reduced dexterity (for example, the elderly), and, in the case of screw locking mechanisms, presents a risk of losing such small screws or, even worse, swallowing one.
Thus, there are ongoing problems when overdenture/denture bar prostheses are used on people with Class II distocclusion and Class III mesiocclusion.